1972 CADILLAC DEVILLE

Typical onset: 50,000-90,000 mi or 40+ years age-related

Symptoms: transmission fluid in radiator or vice versa creating strawberry milkshake appearance, transmission slipping or erratic shifting, overheating transmission, external leaks at cooler line connections

Fix: Replace external cooler lines (original steel lines corrode), flush radiator or replace if contaminated, replace transmission oil cooler in radiator or add external cooler. Figure 4-6 hours labor plus parts. Often discovered too late after fluid mixing has damaged transmission.

Estimated cost: $600-1,200 if caught early, $2,500-4,000 if transmission rebuild required

Typical onset: 70,000-120,000 mi

Symptoms: heavy clunk when shifting into drive or reverse, excessive driveline vibration, visible sag of transmission tailshaft, rattling from underneath at idle

Fix: The rubber transmission mount deteriorates from age and oil contamination. Replacement requires supporting transmission, typically 1.5-2 hours labor. Check nearby crossmember for rust damage while in there.

Estimated cost: $180-350

Typical onset: 80,000-140,000 mi

Symptoms: rough idle and vacuum leaks, coolant loss with no external leaks, oil in coolant or coolant in oil in severe cases, reduced power and poor fuel economy

Fix: The 472 uses composite intake gaskets that fail from age and heat cycling. Manifold removal requires 6-8 hours due to A/C compressor, power steering, and accessory routing on these engines. Critical to check for warped manifold surface and cracked manifold itself during repair.

Estimated cost: $800-1,400

Typical onset: 100,000-150,000 mi

Symptoms: blue smoke on startup, blue smoke during deceleration, oil consumption exceeding 1 quart per 500 miles, fouled spark plugs

Fix: The 472's cast iron heads have bronze valve guides that wear excessively. Requires cylinder head removal, guide replacement or knurling, and valve job. Budget 14-18 hours labor for both heads. Many owners just keep adding oil if compression is still good.

Estimated cost: $1,800-3,200 for proper head rebuild with both heads off

Typical onset: 120,000+ mi or unknown maintenance history

Symptoms: rattling from front of engine at startup, erratic timing and misfiring, rough idle that worsens when warm, check timing with light shows excessive variation

Fix: The 472 uses a long timing chain prone to stretch. Requires front cover removal, harmonic balancer puller, and timing set replacement. Factor 6-8 hours labor. Failure can cause valve-to-piston contact and catastrophic damage, though rare on these low-compression engines.

Estimated cost: $700-1,100

Symptoms: hard starting when warm, flooding and fuel odor, rough idle and hesitation, stalling at stops after highway driving

Fix: The Rochester Quadrajet carburetor develops varnish deposits from modern ethanol fuel, especially in vehicles driven infrequently. Float levels shift, accelerator pump wears out. Proper rebuild takes 3-4 hours including removal and bench time. Replace fuel filter and check fuel pump pressure (5-6 PSI spec). Many shops half-ass these and problems return in months.

Estimated cost: $450-750 for proper rebuild

Typical onset: 80,000+ mi or thermal stress related

Symptoms: ticking sound from engine bay that increases with RPM, exhaust smell in cabin, visible cracks in cast iron manifolds, failed emissions test due to exhaust leaks

Fix: Cast iron manifolds crack from thermal cycling. Replacement requires unbolting from heads and Y-pipe, typically 3-4 hours per side due to tight engine bay. Aftermarket manifolds available but quality varies. Some owners use high-temp epoxy as temporary fix.

Estimated cost: $500-900 per side